Die casting metal alloys



Patented Sept. 10, 1935 UNITED STATES DIE CASTING METAL ALLOYS George H. Starmann, Chicago, Ill., assignor to Apex Smelting (30., Chicago, 111., a corporation of Illinois No Drawing. Application April 2, 1934, Serial No. 718,681

4 Claims.

'I'hepresent invention relates generally to alloys, and more in particular to improved zinc base die casting alloys.

In the past alloys suitable for die casting have included zinc and aluminum. It has been wellknown that zinc-aluminum alloys wherein the zinc constituted a major portion of the alloy underwent a structural change subsequent to solidification, which has beencommonly known as a phase change, such phase change consisting in 1 the formation of two crystalline forms or phases from one phase previously existing. Such a phase change affects the physical properties of the alloy, as for example, increases the density, hardness and tensile strength, and decreases the ductility and impact strength thereof.

It has also been known that these zinc-aluminum alloys were subject to intercrystalline oxidation, which in effect caused the same to grow, warp or lose strength.

Various attempts have been made in the past to correct these interstructural changes which are detrimental to the physical characteristics of the alloy and prohibit their effectiveuse as die casting alloys.

It was found that copper, as well as magnesium, when made a component of the alloys, reacted favorably to retard or inhibit this phase change and to increase the resistance of the alloys to this intercrystalline oxidation. Such metals, however, have not eliminated this phase change or intercrystalline oxidation. The oxidation is present to a considerable extent and in sufilcient amount to cause the alloy to grow, warp and lose strength, especially under favor able conditions, as in the presence of warmth and moisture. r

The present invention comprehends the formation of alloys suitable for use in die casting and the like, which have all of the characteristics of alloys which have been heretofore found satisfactory. such as suflicient fluidity, proper density, hardness, tensile strength, ductility and impact strength without possessing this objectionable phase change and intercrystalline oxidation which resulted in growth of the alloy, especially under favorable conditions, as in the presence of warmth and moisture. The present invention, therefore, contemplates the idea of providing suitable alloys which have no growth whatever, even though subjected to warmth and moisture, and in certain instances, as indicated by various experiments, this growth has been negative, which in eifect indicates a slight shrinkage of the alloy upon solidification and upon ing.

It has been found that when titanium or tantalum are used in small quantities in alloys suitable for use in die casting and the like, that the resulting alloys are substantially or totally free of this phase change, as well as the intercrystalline oxidation.

As an example, the following two alloys were subjected to similar tests as indicated below, with the results as also indicated:

Alloy No. Alloy N0. 2

4 4% aluminum. 4.4% aluminum.

1.75% copper. 1.75% copper.

.03% magnesi- 03% magnesium. um. Balance, zinc. 08% titanium.

Balance, zinc.

Alloy No. 1 Alloy No. 2

10 days 10 days As east in steam As cast in steam at 95 C. at 95 0.

Tensilei strengthun s r square i fclL f 47162 39273 45630 37626 Impact strength- (charpy) as measured on M x 54" bar. Footpounds per square int-hi... 13. 24 2. 18 14. 15 2. 72 Elongation-percent in 2 inchesnilgn 4. 2. 25 3. 90 1.35 Dimensional c nge I growth on 6 bar +00% 0002 It will therefore be seen from the above tests made under similar conditions, that the first alloy' containing no titanium had a growth of .0028", whereas the alloy containing .08% titanium had a negative growth. This negative growth of .000 is negligible inquantity, and

even though this represents shrinkage in the alloy, such shrinkage is not prohibitive and such an alloy can be readily used in die casting or' the like. 1

The following compositions of alloys are given and indicate the percentages of the various elements which can be used for alloys suitable for die casting and the like. F

1. Aluminum 3.0 to 6% copper 0 to 5%, titanium .01 to .5%, balance zinc.

2. Aluminum 3.0 to 6%, copper 0 to 5%, magof titanium in suitable quantities provides an alloy which is free fromphase change, as well as intercrystalline oxidation. V

The resulting alloy possesses the necessary density, hardness, tensile and impact strength,

and ductility for use as indicated. Such alloys can be successfully used and cast in permanent molds, die casting machines or in sand without the deteriorating eiiects due to phase change or intercrystalline oxidation.

While I have herein disclosed illustrative embodiments of the invention, it is to be understood that the invention is not limited thereto nor to the particular constituents, ingredients,

substances or components, but other equivalent substances and other proportions in wide range may beused without departing from the spirit thereof.

Patent No. 2,013,870.-

I claim:

1. A zinc base alloy characterized by the substantially complete elimination of interrystalline oxidation and undesirable dimensional changes, comprising 3.0-6% aluminum, .01-.1% magnesium, .01-1% titanium, and the balance made up substantially of zinc.

2.- A zinc base alloy characterized by the sub- Q sium, about .08% titanium, and the balance made up substantially of zinc.

4. A zinc base alloy characterized by the substantially complete elimination of interciystalline oxidation and undesirable changes, comprising about 4.4% aluminum, about 1.75% copper,

. about .03% magnesium, about .08% titanium,

Septeinber 10. 1935.

"GEORGE H. S'lARMANN.

it is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, second column, lines 10, I6 and 22, claims 2, 3 and 4, after "undesirable insert the word dimensional; and that the said Letters Patent should be read with these corrections therein that -the same may conform to the record of the case of October, A. D. 1935.-

Signed and sealed this 8th day (Seal)- in the Patent Office.

7 Leslie Frazer Acting Commissioner of- Patents.

. of titanium in suitable quantities provides an alloy which is free fromphase change, as well as intercrystalline oxidation. V

The resulting alloy possesses the necessary density, hardness, tensile and impact strength,

and ductility for use as indicated. Such alloys can be successfully used and cast in permanent molds, die casting machines or in sand without the deteriorating eiiects due to phase change or intercrystalline oxidation.

While I have herein disclosed illustrative embodiments of the invention, it is to be understood that the invention is not limited thereto nor to the particular constituents, ingredients,

substances or components, but other equivalent substances and other proportions in wide range may beused without departing from the spirit thereof.

Patent No. 2,013,870.-

I claim:

1. A zinc base alloy characterized by the substantially complete elimination of interrystalline oxidation and undesirable dimensional changes, comprising 3.0-6% aluminum, .01-.1% magnesium, .01-1% titanium, and the balance made up substantially of zinc.

2.- A zinc base alloy characterized by the sub- Q sium, about .08% titanium, and the balance made up substantially of zinc.

4. A zinc base alloy characterized by the substantially complete elimination of interciystalline oxidation and undesirable changes, comprising about 4.4% aluminum, about 1.75% copper,

. about .03% magnesium, about .08% titanium,

Septeinber 10. 1935.

"GEORGE H. S'lARMANN.

it is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, second column, lines 10, I6 and 22, claims 2, 3 and 4, after "undesirable insert the word dimensional; and that the said Letters Patent should be read with these corrections therein that -the same may conform to the record of the case of October, A. D. 1935.-

Signed and sealed this 8th day (Seal)- in the Patent Office.

7 Leslie Frazer Acting Commissioner of- Patents. 

